I imagine that the first film will very much be the softer, more 'cartoon'-ish sort of violence (smacking over the head, and what not), but, by the third film with the Bot5A that the tone and violence will become much grittier ala the Lord of the Rings films. It'll be kind of like what Guillermo talked about on the forums back when he was going to direct and regarding the colour palettes shifting and the notion that by the end of the Hobbit, the fairy tales of Middle Earth are over. So, I very much assume that the violence will reflect that, so as to not make a jarring transition (when viewed in order) to Fellowship's violent, gritty prologue.